Effects of anemia and blood transfusion in acute myocardial infarction in rats

Abstract

The optimal hemoglobin (Hb) level in acute myocardial infarction (MI) is unknown. The goal of this study was to determine the optimal Hb concentration in acute MI and whether transfusion of fresh blood to correct anemia reduces myocardial injury and improves outcome. Anemia was induced in rats by an iron-deficient diet and phlebotomy. MI was induced by left coronary artery ligation. Some rats received transfusion of fresh blood. Survival, hemodynamic measurements, and infarct size were determined 24 hours after MI. Reduction of Hb to 80 to 90 and 70 to 80 g/L decreased 24-hour survival after MI to 42 and 47%, respectively (p < 0.05). Infarct size was increased in both 70 to 80 and 80 to 90 g/L anemic groups compared to the normal Hb group (p < 0.05). Cardiac function was decreased in anemic groups after MI (p < 0.01). Transfusion of fresh blood to increase Hb from 80 to 90 g/L to 100 g/L decreased infarct size (p < 0.05) and improved cardiac function (p < 0.05), and a trend toward better survival (73%) was observed. Transfusion from 80 to 90 g/L Hb to 120 g/L Hb was associated with larger infarct size (p < 0.05), decreased cardiac function (p < 0.05), and no improvement in survival (47%, p = NS). Anemia increases infarct size and decreases cardiac function and survival in acute MI. Transfusion of anemic animals up to 100 g/L Hb with fresh blood reduces infarct size and improves cardiac function. However, transfusion to 120 g/L Hb did not demonstrate any additional benefit and was associated with larger infarcts.